image_types.bbclass: set 'filetype' ext4 feature

image_types.bbclass: set 'filetype' ext4 feature

Generating filesystems with this flag allows more efficient directory
traversals because getdents() returns the filetype in 'd_type' which
allows to avoid an extra lstat() call.

Creating ext4 filesystems with 'mkfs.ext4' sets this flag by default
too.

(From OE-Core rev: 75e077025397f3bde84e60a9da2c0564ade09b39)

Signed-off-by: Enrico Scholz <enrico.scholz@sigma-chemnitz.de>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>